Elements of Music

40 41 coMplEx chord progrEssIons getting out of the box To develop a richer harmonic palette and get out of the IIVVI box, a more complex structure can be developed by borrowing chords from a parallel scale, thus facilitating longer excursions. Because it is the root of a chord that imparts its functionality, we can freely substitute other chords built upon the same scale degree opposite top and still preserve the harmonic essence. So a major subdominant IV can be substituted for a minor one iv, or a minor mediant iii can be replaced with a major mediant bIII and its inflections bIII. As long as basic cadences occasionally occur to reinforce a tonic, chords can be borrowed relatively freely. The dominant seventh chord is wellsuited for substitution because of its symmetrical tritone see below. When the root shifts by a tritone, the 3rd and 7th of each chord exchange places. The spelling of this interval changes enharmonically to preserve the syntax, but the sound is the same. In fact, as we move around the circle of fifths with seventh chords, the 3rd and 7th of each chord exchange places and slip and slide by steps, often referred to as step progressions or guide tones, a reciprocity that maximises the forward drive of harmonic motion. In most chords, it is the root, 3rd and 7th that are sufficient to communicate the harmonic function, so when voicing chords, the 5th can frequently be omitted, since it only reinforces the tonic structurally. If, however, the 5th is altered or b, augmented or diminished, then its colour is included as well. Above A table of substitutions. Secondary dominants act like the primary dominant in that they possess a tritone, and suggest a resolution a fourth up or fifth down. They require a chromatic alteration to the basic scale in use. The new leading tone that results temporarily suggests an alternate key or scale, but this is usually brief, either occurring as a passing chord, or as a tonicization. The presence of borrowed chords weakens the strength of the tonic, but often provides a lovely shading or colour, partly due to their violating our expectations about which chords we expect to hear in a given key. The wellknown song Amazing Grace uses inversions, and a secondary dominant, in this case the V of the subdominant IV. It sounds much like the I chord, only with an added 7th, pointing upwards by a fourth. In Greensleeves we have a truly modal harmonic progression, borrowing freely from the parallel major, and briefly pointing to the relative major in the third and fourth phrases. There are many ways to harmonise these songs, these examples present only one possibility. Amazing Grace Scale Degree 6 6 6 4 Greensleeves